The festival has been celebrated in China for over 1,000 years. It started as a thank-you to the moon for a good harvest at the end of summer. Today, it is mostly about getting together with family.
Mooncakes are the food of the festival. They are small, round, golden cakes with a thick filling - often lotus seed paste or sweet red bean - and beautiful patterns pressed into the top. They are very rich, so usually one mooncake is shared between several people, cut into small slices.
Children love mid-autumn night for the lanterns. They light up paper lanterns shaped like rabbits, dragons, fish and flowers, and walk around outside as the moon rises. In some cities, whole streets are lit up with thousands of glowing lanterns at the same time.
There is a famous old story attached to the festival, about a kind woman called Chang'e who lives on the moon with a small white rabbit. Children look up at the full moon and try to spot the rabbit in the shadows on its surface. (Have a look next full moon - you can sometimes see it!)